It was with some trepidation that we made our way to Audi City London Showroom in Piccadilly, to see the next step in the Forza series. Having loved Forza Motorsport 4 and put plenty of driving hours into it, we were a little concerned about what Forza might have become. We saw the game at E3 and we'd spent time with Playground Games exploring what the game has on offer, but this was the first real chance for free play.

A change of format is something of a bold move, as Forza Horizon looks on paper like a huge step away from the world of Forza Motorsport. As we found out, it is and it isn't. Read on, and we'll try to explain why, based on a couple of hours playing the final code of Forza Horizon.

The game world

The biggest change to Forza in Horizon is the world you inhabit. FM4 has you flying around the globe racing on famous tracks. It's Silverstone, Le Mans, Circuit de Catalunya. Authentic locations replicated with precision and detail. It's a safe, contained world dominated by the raceway.

Forza Horizon, by contrast, is an open-world game. A huge map has been created, based on Colorado, because of the varied environment that part of the world offers. The terrain is one thing, but the reason you're there is also integral to how the game plays.

The Horizon Festival is that reason. The Festival location itself serves as a central gameplay mechanic, so rather than skipping to a lofty garage in a menu, the Festival acts as a sort of home environment. You can return there to buy new cars, perform upgrades and importantly advance in the story that sits behind the game.

In reality, although you can perform these game-world tasks at the festival location itself, many you can just do on the fly. For example, you arrive at a race in the wrong class of car, you get the option to upgrade or downgrade, just as you did in FM4. We also found you could buy a new car when you arrive, so to some degree, the Horizon Festival's function as a hub isn't always entirely obvious.

We spent about two hours playing Forza Horizon so we had a chance to explore some of the map. One of the new elements is that you're not always racing on asphalt. Now you have offroad racing too, so for the first time you'll be able to take some of those great Forza cars and thrash them in their natural environment.

Take, for example, the Audi Sport Quattro. This car cut its teeth in rallying and although a classic racing car, doesn't really fit into the Tarmac world of Forza Motorsport 4. However, throw it around the dirt tracks of Forza Horizon and it all makes sense.

The early stages of the single-player mode of Forza Horizon introduce you to offroad racing. In the couple of races we played we can't say it was hugely different from the road, but we noticed that the track was wide enough to maintain that bustling Forza feel, rather than the enclosed woodland tracks of something like Colin McRae, although there may be those sorts of tracks elsewhere on the map.

It's important to remember that some of the development team at Playground Games worked on titles like Dirt and McRae, so there's experience going into this game, in combination with the automotive pedigree that you expect from a Forza title.

Then you have day and night. You have night racing, you can race as the sun rises, or sets, so you get that beautiful vista with burning skies and the lights of the other cars. It all looks fantastic, as does the Horizon Festival: it's pumping during that day, but really comes to life at night with lasers arching into the sky and fireworks adding to the brilliance.

There's storyline, personality, atmosphere

Working in combination with this central concept of a racing festival, there is something of a storyline pulling things together. This moves Forza Horizon away from a simple credits-for-cars progressive racing game and brings a feeling closer to racing arcade games, like Need for Speed or Burnout Paradise.

Although the plot or storyline of such games does little other than drag you from one driving section to the next, here it lends personality to Forza Horizon. FM4 didn't have personality, just the monotonous narrator saying, "The next race takes place at…", which was really a time to check your phone whilst waiting to get to the start line.

Forza Horizon gives you story from the start. You're introduced to characters, with the opening drive being a race against the current champion, Darius Flynt, quickly followed by a race into the festival where you meet the daisy duke-wearing Alice Hart.

Alice Hart acts as the race director and, from the off, has the feeling of some sort of love interest (in Forza? Really?) Perhaps that never comes to pass, but as we said, there are characters with personality in this new word of racing. Hart talks to you, guides you, encourages you and explains things as you go along.

Through the headset that Hart gives you, you learn about the popularity system and get feedback as you go. It's neat, it works, and it's very different from the straight racing of FM4.

Then you have the festival itself and the game's soundtrack. If you're looking for atmosphere, Forza Horizon brings it by the bucketload. The Horizon Festival was created with input from Rob da Bank, Radio 1 DJ and founder of Bestival, to bring an authentic and excitement to Horizon.

It works too. Driving into the festival you're hit by a wall of noise. You're not just listening to the soundtrack provided by the cars, but the spectators and the music adds real depth here.

There are 66 licensed music tracks divided across three radio stations, so you can switch the background music to suit your tastes. It's current music too, so we caught some Dizzee Rascal, Nero, and raced to Mike and the Womp's Bom Bom. Forza Horizon: we really do like your style of womping.

Behind the wheel

Within this drastically different Forza world, however, this is still very much a Forza driving experience. Arrive at an event and things start to feel familiar. It now has a festival feel, earning your way through coloured wristbands to gain access to more exciting events, but once you're on the grid, Forza drivers will know exactly what to do.

The cars are all here. Although Forza Horizon hasn't yet announced the full list of cars we looked through those on sale and there's a healthy selection of marques and models you'll have seen in Forza Motorsport 4. You'll have to win or buy cars as you go along, although Playground Games told us that if you've been a Forza 4 player, your profile will be recognised and you'll get bonus cars from the off.

Once driving, importantly, the cars behave like Forza cars. They have the authenticity you expect. That classic Mustang wallows in corners, those front wheel drive hot hatches become unpredictable once you upgrade them too far. All the things you know and expect from previous Forza outings you'll find here.

And this is the vital point for Forza Horizon. It's still a car lover's game. It's still a racing game. It might now be called an "action racing game", but it's definitely Forza and you'll know that as soon as you jab the brakes and control that wide drift through the corner, just as you've done in the past.

One of the new gameplay elements is earning points to boost your popularity. Popularity will get you into races, but gaining it is nothing to worry about. There are 35 separate skills that will get you points and the chances are that if you're a Forza driver, you already have those skills.

Drifting is the most obvious example, but airborne overtaking, slingshotting and sideswiping all seemed to earn us points, even if we didn't consciously do anything other than win races by all available means. If you're a Forza player, you'll want to adjust the difficulty right from the start, because we won almost every race with ease, so switching off some of the assists will give you more satisfaction.

With the move from track to open world the consistency of tracks changes too. Driving around the Silverstone Grand Prix circuit is predictable: you have a defined route. In Forza Horizon you might be street racing with railings and walls you can't afford to hit, or wooden fences you can. It changes your driving style slightly, as you're not a slave to the road anymore. Forza Horizon is more forgiving when you deviate off the road: where FM4 was like driving through glue, Horizon will let you cut corners much more effectively, a useful method for passing your opponents, once you know the roads.

Playing for a couple of hours we found plenty of variety. You can choose what races to take, with a selection on offer to navigate to on the map. There are also special events to get to, as well as treasure to find, like a car lost in the mountains. You also get to race rivals to win their car or get involved in private invite-only racing events.

Along the way you'll have to upgrade your car; the starting Scirocco will serve you well, but once upgraded to B class, you can't help feeling that you could do with something a little more stable on the road. With enough credit in our pocket, we bought a Nissan GT-R, an S class car, but then found it was too highly rated for any of the races on offer. At least you can just roam around the world and explore.

Our first impressions

We've seen and played some of what's on offer in Forza Horizon and our fears have been allayed. This isn't Forza Motorsport 5, it isn't straight racing, it's something more. But it hasn't lost the thing we love about Forza. The driving experience is still incredible, but there's way more personality and way more variety.

We already have confirmation that following the game's launch on 26 October, there will be DLC car packs regularly, with an expansion planned for 18 December. This will be a game that grows with you and hopefully, like Forza's of the past, see you coming back to play time and again.

We find ourselves now feeling that Forza Motorsport 4 is just a little too vanilla. It's still an amazing racing game, but Forza Horizon feels like it's going to bring thrills and spills the Forza world hasn't yet seen. Are we excited? You bet we are.